This invention relates to plastic closures for bottles and the like and is more particularly concerned with a threaded plastic cap having an improved integral seal.
The prior art is replete with threaded plastic closures for bottles and the like, including closures having a wide variety of seals. Such seals may include a plurality of annular members that engage one or more of the surfaces constituting the rim of the neck of the bottle. For example, U.S. Pat. No. 4,143,785 discloses a plastic vacuum sealing cap with inner and outer annular flanges extending downwardly from the inner surface of the top wall of the cap, the inner flange extending inwardly at an angle of about 45.degree. to the top wall and being somewhat longer than the outer flange, that extends outwardly at an angle of about 80.degree. to the top wall. U.S. Pat. No, 4,461,392 discloses a threaded plastic bottle cap that includes a similar arrangement of sealing flanges, but in which the cap is provided with an annular groove in the inner surface of the top wall for reception of the inner flange when the cap is fully threaded onto the bottle neck. U.S. Pat. No. 4,645,088 discloses a plastic closure for bottles in which inner and outer annular sealing flanges extend downwardly from a top wall having a concave inner surface. The outer flange has an annular groove that mates with the rim of the neck of a bottle.